Method and apparatus for controlling adaptive reporting in TDD environment

ABSTRACT

A method for enabling a base station to control adaptive reporting in a TDD environment according to one embodiment of the present invention comprises the steps of: transmitting, from a base station to a terminal, an information element including reporting-setting information comprising reporting cycle and reporting offset of channel state information; transmitting information of a UL-DL setting change to the terminal; and receiving the channel state information by using the reporting cycle and the reporting offset of the reporting-setting information corresponding to the changed UL-DL setting.

PRIORITY CLAIM

This application is a continuation of U.S. patent application Ser. No.14/910,490, entitled “Method and Apparatus for Controlling AdaptiveReporting in TDD Environment”, filed May 10, 2016, which is a NationalStage Entry of International Application PCT/KR2014/007404, filed onAug. 8, 2014, and claims priority from and the benefit of Korea PatentApplication No. 10-2013-0094942, filed on Aug. 9, 2013, which are herebyincorporated by reference for all purposes as if fully set forth herein.

The claims in the instant application are different than those of theparent application or other related applications. The Applicanttherefore rescinds any disclaimer of claim scope made in the parentapplication or any predecessor application in relation to the instantapplication. The Examiner is therefore advised that any such previousdisclaimer and the cited references that it was made to avoid, may needto be revisited. Further, any disclaimer made in the instant applicationshould not be read into or against the parent application or otherrelated applications.

TECHNICAL FIELD

The present invention relates to a method and an apparatus forcontrolling adaptive reporting in a Time Division Duplexing (TDD)environment and, more particularly, to a method and an apparatus forperforming a control operation for adaptively reporting a periodicChannel Quality Indicator (CQI)/Precoding Matrix Indicator (PMI).

BACKGROUND ART

With the progress of communication systems, consumers such as companiesand individuals have used a wide variety of wireless terminals.

In current mobile communication systems affiliated with Third GenerationPartnership Project (3GPP), for example, Long Term Evolution (LTE),LTE-Advanced (LTE-A), and the like, as a high-speed and high-capacitycommunication system capable of transmitting and receiving various datasuch as images and wireless data beyond voice-oriented services, it isrequired to develop a technology capable of transmitting a large amountof data coming close to that of a wired communication network. Inaddition, an appropriate error detection scheme in which systemperformance can be improved by minimizing information loss andincreasing system transmission efficiency, becomes an essential element.

Also, in many current communication systems, various Reference Signals(RSs) are used to provide information on a communication environment andthe like to a counterpart apparatus in uplink or downlink. Further,information for identifying a status of a channel, or coding informationis transmitted at a predetermined cycle.

DETAILED DESCRIPTION OF THE INVENTION Technical Problem

The present invention proposes a method for performing a controloperation for adaptively reporting a periodic CQI/PMI for an LTE TDDenhanced Interference Management and Traffic Adaptation (eIMTA)technique and an apparatus implementing the same.

An aspect of the present invention is to implement a method and anapparatus for allowing periodic CQI/PMI reporting, which is based on aRadio Resource Control (RRC) configuration, to be achieved with respectto a dynamically-changed TDD Uplink (UL)-Downlink (DL) configuration (orreconfiguration).

Technical Solution

In accordance with an aspect of the present invention, there is provideda method for controlling adaptive reporting by a base station in a TDDenvironment. The method includes: transmitting an information elementincluding reporting configuration information including a reportingperiodicity and a reporting offset of channel status information, fromthe base station to a user equipment; transmitting information on anUplink (UL)-Downlink (DL) configuration change, from the base station tothe user equipment; and receiving the channel status information byusing a reporting periodicity and a reporting offset of the reportingconfiguration information corresponding to the changed UL-DLconfiguration, by the base station.

In accordance with another aspect of the present invention, there isprovided a method for controlling adaptive reporting by a user equipmentin a TDD environment. The method includes: receiving an informationelement including reporting configuration information including areporting periodicity and a reporting offset of channel statusinformation, from a base station by the user equipment; receivinginformation on an Uplink (UL)-Downlink (DL) configuration change, fromthe base station by the user equipment; and transmitting the channelstatus information by using a reporting periodicity and a reportingoffset of the reporting configuration information corresponding to thechanged UL-DL configuration, by the user equipment.

In accordance with still another aspect of the present invention, thereis provided a base station for controlling adaptive reporting in a TDDenvironment. The base station may include: a control unit for generatingan information element including reporting configuration informationincluding a reporting periodicity and a reporting offset of channelstatus information; a transmission unit for transmitting the generatedinformation element to a user equipment, and transmitting, to the userequipment, information on an Uplink (UL)-Downlink (DL) configurationchange of the user equipment; and a reception unit for receiving asignal from the user equipment, wherein the control unit may control thereception unit to receive indicator information of the user equipment byusing a reporting periodicity and a reporting offset of the reportingconfiguration information corresponding to the changed TDD UL-DLconfiguration.

In accordance with yet another aspect of the present invention, there isprovided a user equipment for controlling adaptive reporting in a TDDenvironment. The user equipment includes: a reception unit forreceiving, from a base station, an information element includingreporting configuration information including a reporting periodicityand a reporting offset of channel status information, and receiving,from the base station, information on an Uplink (UL)-Downlink (DL)configuration change; a transmission unit for transmitting a signal tothe base station; and a control unit for controlling the transmissionunit to transmit the channel status information by using a reportingperiodicity and a reporting offset of the reporting configurationinformation corresponding to the changed UL-DL configuration.

Advantageous Effects

When the present invention is applied, periodic CQI/PMI reporting, whichis based on an RRC configuration, can be performed according to adynamically-changed TDD UL-DL configuration.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a view illustrating an eIMTA deployment scenario, to which thepresent invention may be applied.

FIG. 2 is a view illustrating a dynamic TDD UL-DL configuration.

FIG. 3 is a view illustrating a case where a reporting problem arises inthe situation of a dynamic TDD UL-DL configuration.

FIG. 4 is a view illustrating a case where information required forreporting is configured when a first method according to the presentinvention is applied.

FIG. 5 is a view illustrating the application of an embodiment of thepresent invention.

FIG. 6 is a view illustrating operations between a base station and auser equipment according to an embodiment of the present invention.

FIG. 7 is a view illustrating a process for controlling adaptivereporting by a base station in a TDD environment according to anembodiment of the present invention.

FIG. 8 is a view illustrating a process for controlling adaptivereporting by a user equipment in a TDD environment according to anembodiment of the present invention.

FIG. 9 is a view illustrating a configuration of a base stationaccording to an embodiment of the present invention.

FIG. 10 is a view illustrating a configuration of a user equipmentaccording to an embodiment of the present invention.

FIGS. 11 and 12 are views each illustrating a configuration example of aCQI-ReportPeriodic according to an embodiment of the present invention.

MODE FOR CARRYING OUT THE INVENTION

Hereinafter, exemplary embodiments of the present invention will bedescribed in detail with reference to the exemplary drawings. In thefollowing description, the same components will be designated by thesame reference numerals although they are shown in different drawings.Further, in the following description of the present invention, adetailed description of known functions and configurations incorporatedherein will be omitted when it may make the subject matter of thepresent invention rather unclear.

The wireless communication system may include a User Equipment (UE) anda Base Station (BS or an eNB). Throughout the specifications, the userequipment may be an inclusive concept indicating a user terminalutilized in wireless communication, including a UE (User Equipment) inWCDMA, LTE, HSPA, and the like, and an MS (Mobile station), a UT (UserTerminal), an SS (Subscriber Station), a wireless device, and the likein GSM.

The base station 20 or a cell, may generally refer to a station wherecommunication with the user equipment 10 is performed, and may also bereferred to as a Node-B, an eNB (evolved Node-B), a Sector, a Site, aBTS (Base Transceiver System), an Access Point, a Relay Node, and thelike.

That is, the base station 20 or the cell may be construed as aninclusive concept indicating a portion of an area covered by a BSC (BaseStation Controller) in CDMA, a NodeB in WCDMA, an eNB or a sector (site)in LTE, and the like, and the concept may include various coverageareas, such as a megacell, a macrocell, a microcell, a picocell, afemtocell, a communication range of a relay node, and the like.

In the specification, the user equipment and the base station are usedas two (uplink or downlink) inclusive transceiving subjects to embodythe technology and technical concepts described in the specifications,and may not be limited to a predetermined term or word. As used herein,the user equipment may be called a terminal for short.

In a system, such as LTE and LTE-A, to which the present invention maybe applied, a standard may be developed by configuring an uplink and adownlink based on a single carrier or a pair of carriers. The uplink andthe downlink may transmit control information through a control channel,such as a PDCCH (Physical Downlink Control CHannel), PCFICH (PhysicalControl Format Indicator CHannel), PHICH (Physical Hybrid ARQ IndicatorCHannel), PUCCH (Physical Uplink Control CHannel), and the like, and maybe configured as a data channel, such as PDSCH (Physical Downlink SharedCHannel), PUSCH (Physical Uplink Shared CHannel), and the like, so as totransmit data.

Abbreviations used in this specification are described as follows.

PCell: Primary serving cell

SCell: Secondary serving cell

RS: Reference Signal

CRS: Common Reference Signal

DM-RS: DeModulation Reference Signal

eIMTA: enhanced Interference Management and Traffic Adaptation

CIF: Carrier Indicator Field

CQI: Channel Quality Indicator

PMI: Precoding Matrix Indicator

RI: Rink Inkicator

In this specification, information or an indicator, which indicates achannel status of a DL channel such as a CQI/PMI and an RI, is referredto as “channel status information” or a “channel information indicator.”Also, in this specification, an operation of a UE for transmitting thechannel status information or the channel information indicator isreferred to as “reporting.” For example, an operation of the UE fortransmitting a CQI/PMI is referred to as “CQI/PMI reporting,” and anoperation of the UE for transmitting an RI is referred to as “RIreporting.”

Uplink transmission and downlink transmission may be performed based ona TDD (Time Division Duplex) scheme that performs transmission based ondifferent times, or based on an FDD (Frequency Division Duplex) schemethat performs transmission based on different frequencies. Meanwhile, atimepoint of a downlink and a timepoint of an uplink may bedistinguished in TDD, and when various TDD configurations exist,timepoints may be varied.

Table 1 below is a table showing a TDD configuration. It can be notedthat respective UL-DL configurations have different UL-DL subframetransmission timings.

TABLE 1 UL-DL configurations Uplink-downlink Downlink-to-Uplink Subframenumber configuration Switch-point periodicity 0 1 2 3 4 5 6 7 8 9 0  5ms D S U U U D S U U U 1  5 ms D S U U D D S U U D 2  5 ms D S U D D D SU D D 3 10 ms D S U U U D D D D D 4 10 ms D S U U D D D D D D 5 10 ms DS U D D D D D D D 6  5 ms D S U U U D S U U D

In Table 1, an area indicated by D represents DL and an area indicatedby U represents UL, in a radio frame corresponding to 10 subframes. Srepresents a special subframe that is switched from a DL to a UL on thebasis of a DL-to-UL switch-point periodicity.

Table 2 below shows the value of a DL association set index K in TDD. Khas {k₀, k₁, . . . , k_(M-1)}. Here, elements of the set K are valuesused to indicate a DL subframe corresponding to a UL subframe n-k, asshown in Table 2, and the number of multiple k values associated withone UL subframe is defined as M.

TABLE 2 DL association set index in TDD: {k₀, k₁, . . . , kM⁻¹} UL-DLSubframe n Configuration 0 1 2 3 4 5 6 7 8 9 0 — — 6 — 4 — — 6 — 4 1 — —7, 6 4 — — — 7, 6 4 — 2 — — 8, 7, 4, 6 — — — — 8, 7, 4, 6 — — 3 — — 7,6, 11 6, 5 5, 4 — — — — — 4 — — 12, 8, 7, 11 6, 5, 4, 7 — — — — — — 5 —— 13, 12, 9, 8, 7, 5, 4, 11, 6 — — — — — — — 6 — — 7 7 5 — — 7 7 —

In a UL frame n, response information to a DL signal, DL information, orthe like may be transmitted through a DL subframe (a subframe n-k)having a subframe number before a k value included in K. Table 2signifies a Physical Downlink Shared CHannel (PDSCH)Acknowledgement/Negative-acknowledgement (Ack/Nack) timing.

Meanwhile, the setting of a reporting periodicity and a reportingoffset, to which the value of an I_(CQI/PMI) signaled via RRC is mapped,follows Table 3 below. An I_(CQI/PMI) which indicates the reportingperiodicity and the reporting offset is an example of reportingconfiguration information. The reporting configuration information isinformation indicating a reporting periodicity and a reporting offsetrequired when the UE reports CQI/PMI information or RI information tothe BS. An I_(RI) described below is also an example of the reportingconfiguration information.

TABLE 3 Mapping of I_(CQI/PMI) to N_(pd) and N_(OFFSET) (CQI for TDD)I_(CQI/PMI) Value of N_(pd) Value of N_(OFFSET, CQI) I_(CQI/PMI) = 0 1I_(CQI/PMI) 1 ≤ I_(CQI/PMI) ≤ 5 5 I_(CQI/PMI) − 1   6 ≤ I_(CQI/PMI) ≤ 1510 I_(CQI/PMI) − 6  16 ≤ I_(CQI/PMI) ≤ 35 20 I_(CQI/PMI) − 16 36 ≤I_(CQI/PMI) ≤ 75 40 I_(CQI/PMI) − 36  76 ≤ I_(CQI/PMI) ≤ 155 80I_(CQI/PMI) − 76 156 ≤ I_(CQI/PMI) ≤ 315 160  I_(CQI/PMI) − 156  316 ≤I_(CQI/PMI) ≤ 1023 Reserved

The value of a periodicity to be applied to a serving cell c forperiodic CQI/PMI reporting in TDD is determined according to a TDD UL-DLconfiguration of a PCell. When TDD UL-DL configurations of the PCell are{0, 1, 3, 4, 6}, a reporting periodicity may be set to be N_(pd)=1. Inthis case, the periodicity is equal to 1 ms, and thus, CQI/PMI reportingis performed in all UL subframes.

Meanwhile, when TDD UL-DL configurations of the PCell are {0, 1, 2, 6},the reporting periodicity may be set to be N_(pd)=5. Alternatively, thereporting periodicities may be set to be N_(pd)={10, 20, 40, 80, 160}regardless of the TDD UL-DL configuration of the PCell.

Mapping values for reporting of Rank Indication (RI) in TDD follow areport configuration in Table 4 below.

TABLE 4 Mapping of I_(RI) to M_(RI) and N_(OFFSET, RI) I_(RI) Value ofM_(RI) Value of N_(OFFSET, RI)  0 ≤ I_(RI) ≤ 160 1 −I_(RI) 161 ≤ I_(RI)≤ 321 2 −(I_(RI) − 161) 322 ≤ I_(RI) ≤ 482 4 −(I_(RI) − 322) 483 ≤I_(RI) ≤ 643 8 −(I_(RI) − 483) 644 ≤ I_(RI) ≤ 804 16 −(I_(RI) − 644) 805≤ I_(RI) ≤ 965 32 −(I_(RI) − 805)  966 ≤ I_(RI) ≤ 1023 Reserved

Parameters, that the BS indicates for the above-described CQI/PMI reportand RI report, indicate cqi-pmi-ConfigIndex (I_(CQI/PMI)) orri-ConfigIndex (I_(RI)) to each serving cell in the case of TM 1-9through higher layer signaling, or indicate cqi-pmi-ConfigIndex(I_(CQI/PMI)) or ri-ConfigIndex (I_(RI)) to each Channel StatusInformation (CSI)-process of each serving cell in the case of TM 10through higher layer signaling. Values of a CQI/PMI report periodicityN_(pd) and offset N_(OFFSET, CQI), which enable the identification of asubframe to perform reporting, are derived by applying the parametersand Table 3. Similarly, the RI report also indicates values of aperiodicity M_(RI) and a relative offset N_(OFFSET, RI) on the basis ofthe value of ri-ConfigIndex (I_(RI)) and Table 4.

When one or more CSI-subframe sets are configured for the UE, theCSI-subframe sets are configured as “cqi-pmi-ConfigIndex andri-ConfigIndex for subframe set 1” and “cqi-pmi-ConfigIndex2 andri-ConfigIndex2 for subframe set 2” corresponding to the respectivesubframe sets. In addition, in the case of TM 10, the above-describedparameters may be configured in each CSI-process.

Relevant reporting instances (i.e., a subframe in which reportingoccurs) according to a reporting mode of the UE derive a subframe, inwhich a CQI/PMI or an RI is reported, by using the Equation below. Thefollowing example is an example in a case where a wideband CQI/PMI isconfigured. Specifically, a reporting instance for the wideband CQI/PMIis subframes satisfying Equation 1 below.(10×n _(f) +└n _(s)/2┘−N _(OFFSET,CQI))mod(N _(pd))=0  Equation 1

When RI reporting is configured, a reporting interval of the RIreporting is a value obtained by multiplying M_(RI) by N_(pd), and areporting instance is subframes satisfying Equation 2 below.(10×n _(f) +└n _(s)/2┘−N _(OFFSET,CQI) −N _(OFFSET,RI))mod(N _(pd) ·M_(RI))=0  Equation 2

In addition to the above-described Equations, another Equation may beapplied according to another reporting mode.

Meanwhile, a DL-reference UL-DL configuration according to TDD UL-DLconfigurations of a PCell and an SCell for a serving cell may beconfigured as in Table 5 below.

TABLE 5 DL-reference UL-DL configuration according to UL/DLconfigurations of PCell and SCell for serving cell DL-reference (Primarycell UL/DL configuration, UL/DL Set # Secondary cell UL/DLconfiguration) configuration Set 1 (0, 0) 0 (1, 0), (1, 1), (1, 6) 1 (2,0), (2, 2), (2, 1), (2, 6) 2 (3, 0), (3, 3), (3, 6) 3 (4, 0), (4 ,1),(4, 3), (4, 4), (4, 6) 4 (5, 0), (5, 1), (5, 2), (5, 3), (5, 4), (5, 5),(5, 6) 5 (6, 0), (6, 6) 6 Set 2 (0, 1), (6, 1) 1 (0, 2), (1, 2), (6, 2)2 (0, 3), (6, 3) 3 (0, 4), (1, 4), (3, 4), (6, 4) 4 (0, 5), (1, 5), (2,5), (3, 5), (4, 5), (6, 5) 5 (0, 6) 6 Set 3 (3, 1), (1, 3) 4 (3, 2), (4,2), (2, 3), (2, 4) 5 Set 4 (0, 1), (0, 2), (0, 3), (0, 4), (0, 5), (0,6) 0 (1, 2), (1, 4), (1, 5) 1 (2, 5) 2 (3, 4), (3, 5) 3 (4, 5) 4 (6, 1),(6, 2), (6, 3), (6, 4), (6, 5) 6 Set 5 (1, 3) 1 (2, 3), (2 ,4) 2 (3, 1),(3, 2) 3 (4, 2) 4

Hereinafter, a TDD UE may signify a terminal that transmits/receives asignal to TDD.

i) When Carrier Aggregation (CA) is configured for the TDD UE anddifferent TDD UL-DL configuration values are set (TDD UL-DLconfiguration) for at least two serving cells, a PCell (i.e., a primarycell) always follows a DL-reference UL-DL configuration having a valueidentical to that of a TDD UL-DL configuration of the PCell.

ii) When CA is configured for the TDD UE and different TDD UL-DLconfiguration values are set for at least two serving cells,

ii-1) When the above-described pair (PCell, SCell) belongs to set 1, aDL HARQ-timing is applied to a DL-reference UL/DL configuration for anSCell (i.e., a secondary cell), according to a DL-reference UL-DLconfiguration for set 1. Set 1 has no limit on a scheduling method.

ii-2) Alternatively, when the UE is a terminal supportingself-scheduling, if a pair belonging to set 2 or set 3 is configured,the pair follows a DL-reference UL-DL configuration of set 2 or set 3.

ii-3) Alternatively, when cross-carrier scheduling is configured for theUE (i.e., when the UE is configured to monitor a PDCCH/Enhanced PDCCH(EPDCCH) having a Carrier Indicator Field (CIF)), if a relevant paircorresponds to set 4 or set 5, the relevant pair follows a DL-referenceUL-DL configuration of set 4 or set 5.

ii-4) Specifically, when pairs belonging to set 1 satisfy a UE for whicha CIF is configured or is not configured, set 1 uses a DL-referenceUL-DL configuration in the relevant set 1. In contrast, set 2 and set 3are applied only for the UE for which the CIF is not configured, and set4 and set 5 are applied only for the UE for which the CIF is configured.

iii) When CA is configured for the TDD UE and different TDD UL-DLconfiguration values are set for at least two serving cells, if aDL-reference UL-DL configuration for the at least one serving cell is#5, the UE does not predict that two or more serving cells will beconfigured.

FIG. 1 is a view illustrating an eIMTA deployment scenario, to which thepresent invention may be applied.

Scenario 1 is a scenario in which multiple femtocells are deployed at anidentical carrier frequency. In scenario 2, multiple femtocells aredeployed at an identical carrier frequency, and multiple macrocells aredeployed at an adjacent carrier frequency, wherein all of the macrocellsmay have an identical TDD UL-DL configuration and the femtocells mayadjust a TDD UL-DL configuration. In scenario 3, multiple femtocells aredeployed at an identical carrier frequency, and are located in outdoorareas. In scenario 4, multiple outdoor picocells are deployed at anidentical carrier frequency, and multiple macrocells are deployed atmultiple adjacent carrier frequencies, wherein all of the macrocells mayhave an identical TDD UL-DL configuration and the outdoor picocells mayadjust a TDD UL-DL configuration. Accordingly, small cells (e.g.,picocells or femtocells) except for the macrocells are capable ofchanging a dynamic TDD UL-DL configuration.

Hereinafter, a description will be made of a scheme in which reportingconfiguration information, which may be applied between a relevant BSand a relevant UE, is applied to a dynamic TDD UL-DL in a network (anetwork environment to which a dynamic TDD UL-DL configuration orreconfiguration is applied) in which eIMTA is configured according to anembodiment of the present invention. Reporting information, to which thereporting configuration information is to be applied, may be a CQI/PMIor an RI. The reporting configuration information may be identicallyapplied to a CQI/PMI or an RI. A method and an apparatus for adaptivelyperforming periodic CQI/PMI or RI reporting will be described.

FIG. 2 is a view illustrating a dynamic TDD UL-DL configuration.

FIG. 2 illustrates that a TDD UL-DL configuration for an eIMTA capableUE may be quickly changed as represented by #0, #1, and #2 in a unit oftens of milliseconds according to signaling by an eNB. However, it isproblematic to intactly utilize an existing reporting method in anenvironment illustrated in FIG. 2. This configuration will be describedwith reference to FIG. 3.

FIG. 3 is a view illustrating a case where a reporting problem arises inthe situation of a dynamic TDD UL-DL configuration.

When the above-described method for periodic CQI/PMI reporting (TDD) isintactly applied to eIMTA (i.e., a dynamic TDD UL-DL configurationchange), a case occurs in which periodic CQI/PMI reporting is notcapable of being performed according to a particular TDD UL-DLconfiguration. A radio frame n indicated by reference numeral 310 ofFIG. 3 has a TDD UL-DL configuration of 0, and reporting configurationinformation I_(CQI/PMI) to be applied to the radio frame n is set tohave 0. I_(CQI/PMI)=0 signifies a case where N_(pd) is equal to 1 andN_(OFFSET, CQI) is equal to 0. The reporting configuration informationmay be set to RRC. When, after the radio frame n, a radio frame n+1 isdynamically changed to a TDD UL-DL configuration #2 as indicated byreference numeral 320, periodic CQI/PMI reporting may not be performed.Specifically, the TDD UL-DL configurations are different before andafter a changing boundary between the radio frame n indicated byreference numeral 310 and the radio frame n+1 indicated by referencenumeral 320. Accordingly, when reporting configuration informationidentical to that of the radio frame (the radio frame 310) before theboundary is applied to the radio frame 320, the radio frame 320 isdifferent from the radio frame 310 with respect to a UL-DL subframeconfiguration within a radio frame, and thus, reporting may not beproperly performed, so that there is a need for a solution thereto.

Hereinafter, a description will be made of first and second methods forperforming periodic reporting when a TDD UL-DL configuration isdynamically changed. Changing of the TDD UL-DL configuration may includechanging, by a BS, a TDD UL-DL configuration of a cell; and indicating,by the BS, the changing of the TDD UL-DL configuration to a UE, and theUE may change the TDD UL-DL configuration according to the indicationfrom the BS or at a pre-agreed time point. Hereinafter, the changing ofthe TDD UL-DL configuration includes all of the processes.

A First Method: A Method for Previously Configuring Information Requiredfor Reporting so as to be Applicable to Each TDD UL-DL Configuration.

It is possible to previously configure and use CQI/PMI reportinginformation applicable to each TDD UL-DL configuration or each TDD UL-DLconfiguration set. A particular reporting indicator I_CQI/PMI may bemapped to each TDD UL-DL configuration or each TDD UL-DL configurationset. CQI/PMI reporting information may include information on a CQI/PMIreporting periodicity and a CQI/PMI reporting offset. Thepreviously-configured information may be shared (higher layer signaling)by the BS and the UE, and when the BS changes a TDD UL-DL configuration,the UE may use reporting information corresponding to the changed TDDUL-DL configuration. When the TDD UL-DL configuration is changed, the UEmay perform periodic CQI/PMI reporting on the basis of reportinginformation corresponding to a reporting indicator mapped to the changedTDD UL-DL configuration.

A first method may indicate values of I_(CQI/PMI_i) (N_(pd_i),N_(OFFSET, CQI_i)), which is reporting configuration information that aTDD UL-DL configuration capable of being configured for an eIMTA capableUE may apply, to each TDD UL-DL configuration or each set of TDD UL-DLconfigurations. Here, the value of i may be equal to 7 which is thenumber of all of the current TDD UL-DL configurations, or less. Also, asthe number of TDD UL-DL configurations increases, the value of i mayincrease. Therefore, the values of I_(CQI/PMI_i) which is multiplepieces of reporting configuration information may be indicated to theeIMTA capable UE for periodic CQI/PMI reporting. It is possible todynamically change periodic CQI/PMI reporting suitable for an actual TDDUL-DL configuration, which is dynamically changed, through the indicatedvalues of I_(CQI/PMI_i). The dynamic TDD UL-DL configuration change iscapable of being applied through a PDCCH or an EPDCCH.

For example, multiple pieces of I_(CQI/PMI), which are capable of beingconfigured for each of all available TDD UL-DL configurations, may besignaled to one eIMTA capable UE.

A periodicity of periodic CQI/PMI reporting is set by the BS on thebasis of the scheme. An example of reporting configuration informationto be configured according to TDD UL-DL will be described below.

When the BS changes the TDD UL-DL configuration, the UE connected to therelevant BS previously has the reporting configuration information whichis matched to the changed TDD UL-DL configuration, and thus, the UE mayadaptively apply the reporting configuration information to the changeof a TDD UL-DL in a cell.

When a TDD UL-DL configuration is {0, 3, 4}, reporting configurationinformation may be configured as I_(CQI/PMI_0)=0 (N_(pd_0)=1,N_(OFFSET, CQI_0)=0). In this case, a CQI/PMI reporting indicator,namely, reporting configuration information, may be mapped to 0 withrespect to {0, 3, 4} which is a set of TDD UL-DL configuration values.Here, each number of {0, 3, 4} signifies a TDD UL-DL configurationvalue. A CQI/PMI reporting periodicity and a CQI/PMI reporting offsetmay be configured to respectively have 1 and 0 for the UE on the basisof the mapped CQI/PMI reporting indicator 0.

Specifically, when the TDD UL-DL configuration is changed to oneconfiguration value of {0, 3, 4} according to an indication from the BS,the UE performs periodic CQI/PMI reporting which is based on the CQI/PMIreporting indicator 0.

When a TDD UL-DL configuration is {1, 2}

Reporting configuration information may be configured as1≤I_(CQI/PMI_1)≤5(N_(pd_1)=5, I_(CQI/PMI_1)−1), and one of values withinthe range may be designated and the relevant value may be used asreporting configuration information. In this configuration, a CQI/PMIreporting indicator, namely, reporting configuration information, is setto one of values of 1 to 5 with respect to {1, 2} which is a set of TDDUL-DL configuration values, and the value is previously signaled byusing a higher layer. For example, the reporting configurationinformation may be set to a value of 1. When the TDD UL-DL configurationis changed according to an indication from the BS, if the TDD UL-DLconfiguration is the values of {1, 2}, the UE may perform reporting byapplying “1” which is the signaled reporting configuration information.When a CQI/PMI reporting indicator is applied which is an example of thereporting configuration information, a periodicity is equal to 5 and anoffset is equal to 0.

When a TDD UL-DL configuration is {5, 6} Reporting configurationinformation may be configured as 16≤I_(CQI/PMI_2)≤35(N_(pd_2)=20,I_(CQI/PMI_2)−16), and one of values within the range may be designatedand the relevant value may be used as reporting configurationinformation. Similarly, when the value of the TDD UL-DL configuration isequal to 5 or 6, reporting configuration information, that the UE is touse, may be set to one (e.g., 20) of values of 16 to 35 by the BS, andmay be indicated through higher layer signaling. In this case, when theTDD UL-DL configuration is 5 or 6 according to an indication from theBS, the UE may perform CQI/PMI reporting by applying the reportingconfiguration information of 20 and by using a periodicity of 20 and anoffset of 4.

FIG. 4 is a view illustrating a case where information required forreporting is configured when the first method according to the presentinvention is applied. When wideband CQI/PMI reporting is configured, areporting instance occurs in a UL subframe satisfying(10×n_(f)+└n_(s)/2┘−N_(OFFSET,CQI))mod(N_(pd))=0 which is Equation 1.

Referring to FIG. 4, a radio frame indicated by reference numeral 410has a TDD UL-DL configuration of 0, and thus, a reporting mode is set toI_(CQI/PMI)=0 (N_(pd)=1, N_(OFFSET,CQI)=0). A radio frame indicated byreference numeral 420 has a TDD UL-DL configuration of 2, and thus, areporting mode is set to I_(CQI/PMI)=3 (N_(pd_1)=5, N_(OFFSET,CQI)=2).When the BS maintains the TDD UL-DL configuration to be 0 and changesthe TDD UL-DL configuration to 2, the UE performs reporting by applying0 and 3 which are two pieces of reporting configuration informationrespectively corresponding to the TDD UL-DL configuration of 0 and theTDD UL-DL configuration of 2.

Sets of the TDD UL-DL configuration values may be variously configuredwithin an available range.

A Second Method: Configures TDD Based on a DL Reference Timing

A DL reference timing may be applied in order to perform a continuousDL/UL HARQ operation during a dynamic TDD configuration, and I_(CQI/PMI)capable of supporting periodic CQI/PMI reporting may be indicated basedon the DL reference timing.

More specifically, another periodic CQI/PMI reporting method may beconsidered according to a method of how to indicate a timing with a DLreference timing as a reference. In the present invention, the DLreference timing is considered as a reference, but the present inventionis not limited thereto.

2-1 Case: A DL-Reference UL-DL Configuration by Higher Layer Signaling

In this case, a DL HARQ operation is performed according to a DLreference timing, which has been set by a higher layer, regardless of achange of an actual TDD UL-DL configuration. It goes without saying thata DL reference timing, which is suitable for an actual TDD UL-DLconfiguration, may be set and the BS may determine a DL referencetiming, which is desired to be set, through a separate process. Also,here, there are two different application ranges. Firstly, i) aconfigured DL-reference UL-DL configuration may be applied to allsubframes, or secondly, ii) a DL-reference UL-DL configuration may beapplied to only boundary radio frames in which a TDD UL-DL configurationis changed.

A BS indicates, to an eIMTA capable UE, additional reportingconfiguration information (e.g., the value of I_(CQI/PMI)), which isbased on a DL-reference UL-DL configuration required for an eIMTAoperation, together with the DL-reference UL-DL configuration.Accordingly, the BS determines the value of N_(pd), which is applicableaccording to a TDD UL-DL configuration in the current standards, on thebasis of a DL-reference UL-DL configuration, and indicates the value ofI_(CQI/PMI), which corresponds to the determined value of N_(pd), to theeIMTA capable UE. Another example of the reporting configurationinformation may also include I_(RI), and the two types of indicationvalues may be configured within one information element.

FIG. 5 is a view illustrating the application of an embodiment of thepresent invention.

FIG. 5 illustrates an example of a case to which i) a DL-reference UL-DLconfiguration, that a higher layer signals, is applied to all of thesubframes in the 2-1 case. FIG. 5 illustrates a reporting time period(boundary radio frames) to which a DL-reference UL-DL configuration #2,that the higher layer configures, may be applied. 3 (which correspondsto N_(pd)=5), which is the value of additionally-indicated I_(CQI/PMI)which is based on the configured DL-reference UL-DL configuration, isapplied to the boundary radio frames. As another example, a relevantDL-reference UL-DL configuration and I_(CQI/PMI) (N_(pd)=5) may beapplied to only the boundary radio frames indicated by reference numeral510.

Although a DL-reference UL-DL configuration is considered as a referenceindicating the above-described value of I_(CQI/PMI), in this regard, thevalue of I_(CQI/PMI) may be set with subframes all having a common ULsubframe as a reference.

2-2 Case: A DL-Reference UL-DL Configuration According to an Implicit orFixed Scheme

In this case, a method is provided for selecting a DL-reference UL-DLconfiguration which is applicable according to a change of an actual TDDUL-DL configuration. The method is a scheme for selecting a DL DL-ULreference timing, which may be applied to an SCell, according to TDDUL-DL configurations of a PCell and an SCell, and in eIMTA, enables anappropriate DL-reference UL-DL configuration to be selected according toTDD UL-DL configurations before and after a boundary radio frame, inwhich an actual TDD UL-DL configuration is changed, in the boundaryradio frame. Accordingly, in the 2-2 case, the selected DL-referenceUL-DL configuration may be applied to only a boundary radio frame.

In the 2-2 case, the above-described first method may be applied. Theapplication of the second method and that of the first method in the 2-2case are only different from each other with respect to the position ofa subframe to which a DL-reference UL-DL configuration is applied, andthere is no difference between the application of the second method andthat of the first method in the 2-2 case.

In order to perform reporting by using the second method, the UE mayoperate as follows.

The value of a periodicity, which is to be applied to a serving cell cfor periodic CQI/PMI reporting in TDD, may be determined according to aDL-reference UL-DL configuration of a PCell. When DL-reference UL-DLconfigurations of the PCell are {0, 1, 3, 4, 6}, a reporting periodicitymay be set to be N_(pd)=1. In this case, the reporting periodicity isequal to 1 ms, and thus, CQI/PMI reporting is performed in all of the ULsubframes.

Meanwhile, when DL-reference UL-DL configurations of the PCell are {0,1, 2, 6}, the reporting periodicity may be set to be N_(pd)=5.Alternatively, the reporting periodicities may be set to be N_(pd)={10,20, 40, 80, 160} regardless of the DL-reference UL-DL configuration ofthe PCell.

Table 6 below describes a configuration of CQI-ReportPeriodic ofCQI-ReportConfig information elements required to indicate I_(CQI/PMI)and I_(RI) in the case of RRC signaling as an embodiment forimplementing the present invention.

TABLE 6 Configuration of CQI-ReportPeriodic CQI-ReportPeriodic ::=CHOICE {  release NULL,  setup SEQUENCE {   cqi-PUCCH-ResourceIndexINTEGER (0..1185),   cqi-pmi-ConfiqIndex INTEGER (0..1023),  cqi-FormatIndicatorPeriodic CHOICE {    widebandCQI  NULL,   subbandCQI  SEQUENCE {    k INTEGER (1..4)    }   },   ri-ConfigIndexINTEGER (0..1023) OPTIONAL, --Need OR   simultaneousAckNackAndCQIBOOLEAN  } }

cqi-pmi-ConfigIndex is a parameter which indicates I_(CQI/PMI), andri-ConfigIndex is a parameter which indicates I_(RI).CQI-ReportPeriodic, which includes the two parameters, represents RRCsignaling, and multiple RRC signalings may be configured for eachcarrier. Multiple values of I_(CQI/PMI_i) (0<i<7) may indicate valuescorresponding to all TDD UL-DL configurations.

FIG. 6 is a view illustrating operations between a BS and a UE accordingto an embodiment of the present invention. Referring to FIG. 6, in stepS630, the eNB 610, which is a BS, transmits eIMTA higher layerconfiguration information to the UE 620. The configuration informationincludes a DL or UL-reference UL-DL configuration and reportingconfiguration information. The reporting configuration informationincludes CQI/PMI reporting configuration information and/or RI reportingconfiguration information. At this time, the UL-DL configuration mayinclude applicable reporting configuration information, and multipleUL-DL configurations may also include one applicable piece of reportingconfiguration information, as described above. Alternatively,DL-reference UL-DL reporting configuration information, which is not aTDD UL-DL configuration, may be included, and in this regard, theabove-described DL-reference UL-DL configuration also corresponds to aTDD UL-DL configuration. Accordingly, a scheme for transmitting thereporting configuration information may be implemented as in the case ofa TDD UL-DL configuration.

In step S640, the UE 620 identifies and applies the configurationprovided by the eNB 610. At this time, the UE 620 applies periodicCQI/PMI reporting or periodic RI reporting by applying an embodiment ofthe present invention. In this regard, the UE 620 may apply pieces ofreporting configuration information corresponding to all of the TDDUL-DL configurations as in the above-described first method, or mayapply reporting configuration information corresponding to aDL-reference UL-DL configuration as in the second method.

Thereafter, in steps S650 and S660, the eNB 610 indicates, to the UE620, a change of a TDD UL-DL configuration by using physical layersignaling. In steps S655 and S665, the UE 620 performs reporting byapplying a reporting periodicity and a reporting offset, whichcorrespond to the relevant reporting configuration information,according to the change.

The UE 620 may apply reporting configuration information correspondingto the TDD UL-DL configuration as in the above-described first method,or may identify a DL-reference UL-DL configuration by using the TDDUL-DL configuration and may apply reporting configuration informationcorresponding to the identified DL-reference UL-DL configuration, as inthe second method. In the case of the second method, the UE 620 mayapply the reporting configuration information to all of the TDD UL-DLconfigurations, or may apply the reporting configuration information toboundary radio frames in which a UL-DL configuration is changed.

FIG. 7 is a view illustrating a process for controlling adaptivereporting by a BS in a TDD environment according to an embodiment of thepresent invention.

In step S710, the BS generates an information element includingreporting configuration information to be applied to either of a TDDUL-DL configuration and a DL-reference UL-DL configuration. Next, inS720, the BS transmits the generated information element through higherlayer signaling. In step S730, after the TDD UL-DL configuration ischanged, the BS receives reporting from the UE by using a reportingperiodicity and a reporting offset of the reporting configurationinformation corresponding to the changed TDD UL-DL configuration. Boththe reporting configuration information corresponding to the TDD UL-DLconfiguration and reporting configuration information corresponding to aDL-reference UL-DL configuration derived from the TDD UL-DLconfiguration may be applied as embodiments of the present invention.

The change may be performed according to an indication from the BS, ormay be performed according to an indication from another BS, a RemoteRadio Head (RRH), or the like that is controlled by the BS or cooperateswith the BS. Alternatively, the change may be performed without aseparate indication at a time point which is agreed upon with the UE soas to have predetermined time intervals. The examples of the change arenot limited to the description.

More specifically, in order to implement the above-described firstmethod as an embodiment of the present invention, the informationelement includes one or more pieces of reporting configurationinformation to be applied to one or more TDD UL-DL configurations. Thatis, one piece of reporting configuration information, which isapplicable to one or more TDD UL-DL configurations, may exist, and themultiple pieces of reporting configuration information may exist inassociation with the number of multiple TDD UL-DL configurations. Forexample, I_(CQI/PMI_i) or I_(RI_i), which is one piece of reportingconfiguration information, may be configured for each TDD UL-DLconfiguration represented by i, a UL-DL configuration may be configuredas a set represented by i, and I_(CQI/PMI_i) or I_(RI_i) may beconfigured which is reporting configuration information applied to theset i.

Meanwhile, in the second method, reporting configuration information maybe reporting configuration information applied to a DL-reference UL-DLconfiguration. In this case, reception step S730 may be implemented suchthat the BS receives reporting from the UE by using a reportingperiodicity and a reporting offset of the reporting configurationinformation corresponding to a DL-reference UL-DL configurationidentified based on the TDD UL-DL configuration. For example, when aUL-DL configuration of an SCell is 2, a UL-DL configuration of a PCellis 2, and the UL-DL configuration of the SCell and that of the PCellcorrespond to set 1, if Table 5 is applied, a DL-reference UL-DLconfiguration is 2. The BS receives reporting from the UE by using areporting periodicity and a reporting offset which are indicated byI_(CQI/PMI) or I_(RI) which is reporting configuration informationcorresponding to a configuration of 2.

A method which uses the reporting configuration information of theDL-reference UL-DL configuration may be applied to all of the radioframes or may be applied to only a boundary radio frame, as describedabove with reference to FIG. 5. In this case, in reception step S730,the BS may receive reporting from the UE by using a reportingperiodicity and a reporting offset of the reporting configurationinformation corresponding to a DL-reference UL-DL configurationidentified based on the TDD UL-DL configuration in the boundary radioframe.

Also, a DL-reference UL-DL configuration may be selected according tothe implicit or fixed scheme as described in the 2-2 case. In this case,in reception step S730, the BS receives reporting from the UE accordingto reporting configuration information determined according to TDD UL-DLconfigurations before and after the change. The determined reportingconfiguration information is configured according to the implicit orfixed scheme between the BS and the UE, and thus a DL-reference UL-DLconfiguration, to which the reporting configuration information is to beapplied, may be predetermined in a network design process, or may bepredetermined in such a manner that the BS possesses various selectionitems and signals a particular selection item to UEs.

FIG. 8 is a view illustrating a process for controlling adaptivereporting by a UE in a TDD environment according to an embodiment of thepresent invention.

In step S810, the UE receives an information element, which includesreporting configuration information to be applied to either of a TDDUL-DL configuration and a DL-reference UL-DL configuration, from the BSthrough higher layer signaling. Then, after the TDD UL-DL configurationis changed according to a previously-agreed scheme in step S820, in stepS830, the UE transmits reporting by using a reporting periodicity and areporting offset of the reporting configuration information related to aDL-reference UL-DL configuration corresponding to the changed TDD UL-DLconfiguration or the changed TDD UL-DL. Both the reporting configurationinformation corresponding to the TDD UL-DL configuration and reportingconfiguration information corresponding to a DL-reference UL-DLconfiguration derived from the TDD UL-DL configuration may be applied asembodiments of the present invention.

The change may be performed according to an indication from the BS, ormay be performed according to an indication from another BS, an RRH, orthe like that is controlled by the BS or cooperates with the BS.Alternatively, the change may be performed without a separate indicationat a time point which is agreed upon with the BS so as to havepredetermined time intervals. The examples of the change are not limitedto the description.

More specifically, in order to implement the above-described firstmethod as an embodiment of the present invention, the informationelement includes one or more pieces of reporting configurationinformation to be applied to one or more UL-DL configurations. That is,one piece of reporting configuration information, which is applicable toone or more TDD UL-DL configurations, may exist, and the multiple piecesof reporting configuration information may exist in association with thenumber of multiple TDD UL-DL configurations. For example, I_(CQI/PMI_i)or I_(RI_i), which is one piece of reporting configuration information,may be configured for each TDD UL-DL configuration represented by i, aTDD UL-DL configuration may be configured as a set represented by i, andI_(CQI/PMI_i) or I_(RI_i) may be configured which is reportingconfiguration information applied to the set i.

Meanwhile, in the second method, reporting configuration information maybe reporting configuration information applied to a DL-reference UL-DLconfiguration. In this case, transmission step S830 may be implementedsuch that the UE transmits reporting by using a reporting periodicityand a reporting offset of the reporting configuration informationcorresponding to a DL-reference UL-DL configuration identified based onthe TDD UL-DL configuration. For example, when a TDD UL-DL configurationof an SCell is 2, a TDD UL-DL configuration of a PCell is 2, and theUL-DL configuration of the SCell and that of the PCell correspond to set1, if Table 5 is applied, a DL-reference UL-DL configuration is 2. TheUE transmits reporting by using a reporting periodicity and a reportingoffset which are indicated by I_(CQI/PMI) or I_(RI) which is reportingconfiguration information corresponding to a configuration of 2.

A method which uses the reporting configuration information of theDL-reference UL-DL configuration may be applied to all of the subframesor may be applied to only subframes within a boundary radio frame, asdescribed above with reference to FIG. 5. In this case, in transmissionstep S830, the UE may transmit reporting by using a reportingperiodicity and a reporting offset of the reporting configurationinformation corresponding to a DL-reference UL-DL configurationidentified based on the TDD UL-DL configuration in the boundarysubframes.

Also, a DL-reference UL-DL configuration may be selected according tothe implicit or fixed scheme as described in the 2-2 case. In this case,in transmission step S830, the UE transmits reporting according toreporting configuration information determined according to TDD UL-DLconfigurations before and after the change. The determined reportingconfiguration information is configured according to the implicit orfixed scheme between the BS and the UE, and thus a DL-reference UL-DLconfiguration, to which the reporting configuration information is to beapplied, may be predetermined in a network design process, or may bepredetermined in such a manner that the BS possesses various selectionitems and signals a particular selection item to UEs.

FIG. 9 is a view illustrating a configuration of a BS according to anembodiment of the present invention.

The configuration of the BS 900 is described. The BS 900 includes acontrol unit 920, a reception unit 910, and a transmission unit 930. Thecontrol unit 920 generates an information element which includesreporting configuration information to be applied to either of a TDDUL-DL configuration and a DL-reference UL-DL configuration, and thetransmission unit 930 transmits the generated information elementthrough higher layer signaling. The reception unit 910 receives a signalfrom the UE. After the control unit 920 changes the TDD UL-DLconfiguration, the control unit 920 may control the reception unit 910to receive reporting from the UE by using a reporting periodicity and areporting offset of the reporting configuration informationcorresponding to the changed TDD UL-DL configuration, and enables the BSto control adaptive reporting in a TDD environment. Both the reportingconfiguration information corresponding to the TDD UL-DL configurationand reporting configuration information corresponding to a DL-referenceUL-DL configuration derived from the TDD UL-DL configuration may beapplied as embodiments of the present invention.

The change of the TDD UL-DL configuration may be performed according toan indication from the BS, or may be performed according to anindication from another BS, an RRH, or the like that is controlled bythe BS or cooperates with the BS. Alternatively, the change may beperformed without a separate indication at a time point which is agreedupon with the UE so as to have predetermined time intervals. Theexamples of the change are not limited to the description.

More specifically, in order to implement the above-described firstmethod as an embodiment of the present invention, the informationelement includes one or more pieces of reporting configurationinformation to be applied to one or more TDD UL-DL configurations. Thatis, one piece of reporting configuration information, which isapplicable to one or more UL-DL configurations, may exist, and themultiple pieces of reporting configuration information may exist inassociation with the number of multiple TDD UL-DL configurations. Forexample, I_(CQI/PMI_i) or I_(RI_i), which is one piece of reportingconfiguration information, may be configured for each TDD UL-DLconfiguration represented by i, a TDD UL-DL configuration may beconfigured as a set represented by i, and I_(CQI/PMI_i) or I_(RI_i) maybe configured which is reporting configuration information applied tothe set i.

Meanwhile, in the second method, reporting configuration information maybe reporting configuration information applied to a DL-reference UL-DLconfiguration. In this case, the control unit 920 may control thereception unit to receive reporting from the UE by using a reportingperiodicity and a reporting offset of the reporting configurationinformation corresponding to a DL-reference UL-DL configurationidentified based on the TDD UL-DL configuration. For example, when a TDDUL-DL configuration of an SCell is 2, a UL-DL configuration of a PCellis 2, and the UL-DL configuration of the SCell and that of the PCellcorrespond to set 1, if Table 5 is applied, a DL-reference UL-DLconfiguration is 2. The BS receives reporting from the UE by using areporting periodicity and a reporting offset which are indicated byI_(CQI/PMI) or I_(RI) which is reporting configuration informationcorresponding to a configuration of 2.

A method which uses the reporting configuration information of theDL-reference UL-DL configuration may be applied to all of the radioframes or may be applied to only a boundary radio frame, as describedabove with reference to FIG. 5. In this case, the control unit 920 maycontrol the reception unit to receive reporting from the UE by using areporting periodicity and a reporting offset of the reportingconfiguration information corresponding to a DL-reference UL-DLconfiguration identified based on the TDD UL-DL configuration in theboundary radio frame.

Also, a DL-reference UL-DL configuration may be selected according tothe implicit or fixed scheme as described in the 2-2 case. In this case,the control unit 920 controls the reception unit to receive reportingfrom the UE according to reporting configuration information determinedaccording to TDD UL-DL configurations before and after the change. Thedetermined reporting configuration information is configured accordingto the implicit or fixed scheme between the BS and the UE, and thus aDL-reference UL-DL configuration, to which the reporting configurationinformation is to be applied, may be predetermined in a network designprocess, or may be predetermined in such a manner that the BS possessesvarious selection items and signals a particular selection item to UEs.

FIG. 10 is a view illustrating a configuration of a UE according to anembodiment of the present invention. The configuration of the UE 1000 isdescribed. The UE 1000 includes a control unit 1020, a reception unit1010, and a transmission unit 1030. More specifically, the receptionunit 1010 of the UE receives an information element, which includesreporting configuration information to be applied to either of a TDDUL-DL configuration and a DL-reference UL-DL configuration, from the BSthrough higher layer signaling. The transmission unit 1030 transmits asignal to the BS. After the TDD UL-DL configuration is changed accordingto a previously-agreed scheme, the control unit 1020 controls thetransmission unit 1030 to transmit reporting by using a reportingperiodicity and a reporting offset of the reporting configurationinformation corresponding to the changed TDD UL-DL configuration. Boththe reporting configuration information corresponding to the TDD UL-DLconfiguration and reporting configuration information corresponding to aDL-reference UL-DL configuration derived from the TDD UL-DLconfiguration may be applied as embodiments of the present invention.

The change of the TDD UL-DL configuration may be performed according toan indication from the BS, or may be performed according to anindication from another BS, an RRH, or the like that is controlled bythe BS or cooperates with the BS. Alternatively, the change may beperformed without a separate indication at a time point which is agreedupon with the BS so as to have predetermined time intervals. Theexamples of the change are not limited to the description.

More specifically, in order to implement the above-described firstmethod as an embodiment of the present invention, the informationelement includes one or more pieces of reporting configurationinformation to be applied to one or more TDD UL-DL configurations. Thatis, one piece of reporting configuration information, which isapplicable to one or more TDD UL-DL configurations, may exist, and themultiple pieces of reporting configuration information may exist inassociation with the number of multiple TDD UL-DL configurations. Forexample, I_(CQI/PMI_i) or I_(RI_i), which is one piece of reportingconfiguration information, may be configured for each TDD UL-DLconfiguration represented by i, a TDD UL-DL configuration may beconfigured as a set represented by i, and I_(CQI/PMI_i) or I_(RI_i) maybe configured which is reporting configuration information applied tothe set i.

Meanwhile, in the second method, reporting configuration information maybe reporting configuration information applied to a DL-reference UL-DLconfiguration. In this case, the control unit 1020 may control thetransmission unit 1030 such that the UE transmits reporting by using areporting periodicity and a reporting offset of the reportingconfiguration information corresponding to a DL-reference UL-DLconfiguration identified based on the TDD UL-DL configuration. Forexample, when a TDD UL-DL configuration of an SCell is 2, a TDD UL-DLconfiguration of a PCell is 2, and the UL-DL configuration of the SCelland that of the PCell correspond to set 1, if Table 5 is applied, aDL-reference UL-DL configuration is 2. The UE transmits reporting byusing a reporting periodicity and a reporting offset which are indicatedby I_(CQI/PMI) or I_(RI) which is reporting configuration informationcorresponding to a configuration of 2.

A method which uses the reporting configuration information of theDL-reference UL-DL configuration may be applied to all of the radioframes or may be applied to only a boundary radio frame, as describedabove with reference to FIG. 5. In this case, the control unit 1020 maycontrol the transmission unit 1030 to transmit reporting by using areporting periodicity and a reporting offset of the reportingconfiguration information corresponding to a DL-reference UL-DLconfiguration identified based on the TDD UL-DL configuration in theboundary radio frame.

Also, a DL-reference UL-DL configuration may be selected according tothe implicit or fixed scheme as described in the 2-2 case. In this case,the control unit 1020 controls the transmission unit 1030 such that theUE transmits reporting according to reporting configuration informationdetermined according to TDD UL-DL configurations before and after thechange. The determined reporting configuration information is configuredaccording to the implicit or fixed scheme between the BS and the UE, andthus a DL-reference UL-DL configuration, to which the reportingconfiguration information is to be applied, may be predetermined in anetwork design process, or may be predetermined in such a manner thatthe BS possesses various selection items and signals a particularselection item to UEs.

The above-described reporting configuration information may betransmitted according to a scheme shown in Table 6. In Table 6,“cqi-pmi-ConfigIndex” or “ri-ConfigIndex” may increase according to thenumber of TDD UL-DL configurations or DL-reference UL-DL configurations,or the number of sets of UL-DL configurations or DL-reference UL-DLconfigurations. The reconfiguration of a configuration ofCQI-ReportPeriodic in a case where K pieces of reporting configurationinformation are configured is illustrated in FIGS. 11 and 12. Aconfiguration example described below may be an embodiment of thepresent invention, and when TDD UL-DLs are determined as a setdifferently from the configuration example, reporting configurationinformation may be separately combined to the relevant set.

FIGS. 11 and 12 are views each illustrating a configuration example of aCQI-ReportPeriodic according to an embodiment of the present invention.

Referring to FIG. 11, “cqi-pmi-ConfigIndexes” or “ri-ConfigIndexes” tobe applied to a k number of UL-DL configurations are included in aconfiguration example of CQI-ReportPeriodic as indicated by referencenumerals 1110 and 1120. k signifies a maximum number which may be set,and cqi-pmi-ConfigIndex_0, cqi-pmi-ConfigIndex_1, . . . ,cqi-pmi-ConfigIndex_k represent I_(CQI/PMI_0), I_(CQI/PMI_1), . . . ,I_(CQI/PMI_k), respectively. ri-ConfigIndex_0, ri-ConfigIndex_1, . . . ,ri-ConfigIndex_k represent I_(RI_0), I_(RI_1), . . . , I_(RI_k),respectively.

Referring to FIG. 12, REPORT_ConfigType for each of a k number of reportconfigurations is defined as indicated by reference numeral 1230, andthe types indicate multiple pieces of reporting configurationinformation as indicated by reference numerals 1210 and 1220. As aresult, values of I_(CQI/PMI_0), I_(CQI/PMI_1), . . . , I_(CQI/PMI_k)configure cqi-pmi-ConfigIndex_r12, and values of I_(RI_0), I_(RI_1), . .. , I_(RI_k) configure ri-ConfigIndex_r12.

The embodiments of the present invention relates to the periodic CQI/PMIreporting method and the apparatus for the same, which are more adaptivebetween the UE, for which an eIMTA technique is configured, and the BS.The method and the apparatus allow periodic CQI/PMI reporting to besupported in eIMTA for controlling interference between the BSs andadaptive traffic in an LTE TDD system. When the present invention isapplied, periodic CQI/PMI reporting, which is based on an RRCconfiguration, can be performed according to a dynamically-changed TDDUL-DL configuration. Specifically, when the above-described BS and UEare implemented, periodic CQI/PMI reporting, which is more adaptive andappropriate, can be smoothly performed according to adynamically-changed TDD UL-DL configuration.

Although a preferred embodiment of the present invention has beendescribed for illustrative purposes, those skilled in the art willappreciate that various modifications, additions and substitutions arepossible, without departing from the scope and spirit of the inventionas disclosed in the accompanying claims. Therefore, the embodimentsdisclosed in the present invention are intended to illustrate the scopeof the technical idea of the present invention, and the scope of thepresent invention is not limited by the embodiment. The scope of thepresent invention shall be construed on the basis of the accompanyingclaims in such a manner that all of the technical ideas included withinthe scope equivalent to the claims belong to the present invention.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35 U.S.C. § 119(a) on PatentApplication No. 10-2013-0094942, filed in Korea on Aug. 9, 2013, theentire contents of which are hereby incorporated by reference. Inaddition, this application claims priority in countries, other than theU.S., with the same reason based on the Korean Patent Application, theentire contents of which are hereby incorporated by reference.

The invention claimed is:
 1. A method for controlling adaptive reportingby a base station in a Time Division Duplexing (TDD) environment, themethod comprising: at the base station in the TDD environment:transmitting, to a user equipment, a downlink (DL)-reference uplink(UL)-DL configuration for the user equipment via higher layer signaling;transmitting, to the user equipment, information on an UL-DLconfiguration change for a cell on a physical downlink control channel(PDCCH) or enhanced PDCCH (EPDCCH), wherein the UL-DL configurationchange results in a corresponding UL-DL configuration that is differentfrom the DL-reference UL-DL configuration; performing UL reception andDL transmission for the cell according to the corresponding UL-DLconfiguration; and performing DL hybrid automatic request (HARQ)operation for the cell according to a timing based on the DL-referenceUL-DL configuration.
 2. The method of claim 1, wherein said performingDL HARQ operation according to a timing based on the DL-reference UL-DLconfiguration is performed regardless of the UL-DL configuration change.3. The method of claim 1, wherein the cell is a PCell for the userequipment operating in a first TDD mode.
 4. The method of claim 1, themethod further comprising: transmitting, to the user equipment,reporting configuration information, I_(CQI/PMI), which indicates thereporting periodicity and the reporting offset for periodic channelstatus information reporting, wherein the reporting configurationinformation, I_(CQI/PMI), is applied to the DL-reference UL-DLconfiguration.
 5. The method of claim 1, the method further comprising:transmitting, to the user equipment, reporting configurationinformation, I_(CQI/PMI), which indicates the reporting periodicity andthe reporting offset for periodic channel status information reporting,wherein the reporting configuration information, I_(CQI/PMI), is appliedto a common UL subframe as a reference.
 6. The method of claim 1,wherein the timing comprises a set of one or more k values, whereinelements of the set indicate Acknowledgement/Negative-acknowledgement(Ack/Nack) timing in a UL subframe n in response to a transmission in DLsubframe n-k.
 7. A base station (BS) configured for controlling adaptivereporting in a Time Division Duplexing (TDD) environment, the BScomprising: a radio; and a processing element configured to cause the BSto: transmit, to a user equipment (UE), a downlink (DL)-reference uplink(UL)-DL configuration for the UE via higher layer signaling; transmit,to the UE, information on an UL-DL configuration change for a cell on aphysical downlink control channel (PDCCH) or enhanced PDCCH (EPDCCH),wherein the UL-DL configuration change results in a corresponding UL-DLconfiguration that is different from the DL-reference UL-DLconfiguration; perform UL reception and DL transmission for the cellaccording to the corresponding UL-DL configuration; and perform DLhybrid automatic request (HARQ) operation for the cell according to atiming based on the DL-reference UL-DL configuration.
 8. The BS of claim7, wherein to perform DL HARQ operation, the processing element isfurther configured to cause the BS to: apply an association set indexcomprising a k value; transmit, to the UE, a message on a physicaldownlink shared channel (PDSCH) during a first subframe (n-k); andreceive a HARQ response associated with the message from the UE during asecond subframe (n).
 9. The BS of claim 8, wherein said performing DLHARQ operation according to a timing based on the DL-reference UL-DLconfiguration is performed regardless of the UL-DL configuration change.10. The BS of claim 7, wherein the processing element is furtherconfigured to cause the BS to: transmit, to the user equipment,reporting configuration information, I_(CQI/PMI), which indicates thereporting periodicity and the reporting offset for periodic channelstatus information reporting, wherein the reporting configurationinformation, I_(CQI/PMI), is applied to the DL-reference UL-DLconfiguration.
 11. The BS of claim 7, wherein the processing element isfurther configured to cause the BS to: transmit, to the user equipment,reporting configuration information, I_(CQI/PMI), which indicates thereporting periodicity and the reporting offset for periodic channelstatus information reporting, wherein the reporting configurationinformation, I_(CQI/PMI), is applied to a common UL subframe as areference.
 12. The BS of claim 7, wherein the DL-reference UL-DLconfiguration also corresponds to a TDD UL-DL configuration.
 13. A basestation (BS) configured for operation in a Time Division Duplexing (TDD)environment, the BS comprising: a radio; and a processing elementconfigured to cause the BS to: transmit, to a user equipment, a downlink(DL)-reference uplink (UL)-DL configuration for the user equipment viahigher layer signaling; determine reporting configuration information,wherein the reporting configuration information includes a valuecorresponding a reporting periodicity and a reporting offset of channelstatus information based in part on the DL-reference UL-DLconfiguration; transmit, to the user equipment, an information elementincluding the reporting configuration; transmit, to the user equipment,information on an UL-DL configuration change on a physical downlinkcontrol channel (PDCCH) or enhanced PDCCH (EPDCCH), wherein the UL-DLconfiguration change results in a corresponding UL-DL configuration thatis different from the DL-reference UL-DL configuration; perform, withthe user equipment, UL reception and DL transmission according to thecorresponding UL-DL configuration; and receive, from the user equipment,the channel status information according to the DL-reference UL-DLconfiguration and reporting configuration information.
 14. The BS ofclaim 13, wherein the channel status information comprises ChannelQuality Indicator.
 15. The BS of claim 13, wherein the channel statusinformation comprises Precoding Matrix Indicator.
 16. The BS of claim13, wherein the higher layer signaling comprises radio resource controlsignaling.
 17. The BS of claim 13, wherein the receiving the channelstatus information from the user equipment occurs after saidtransmitting information on the UL-DL configuration change.
 18. The BSof claim 13, wherein the processing element is further configured tocause the BS to: perform a DL HARQ operation according to a timing basedon the DL-reference UL-DL configuration regardless of the UL-DLconfiguration change.
 19. The BS of claim 18, wherein to perform DL HARQoperation, the processing element is further configured to cause the BSto: apply an association set index comprising a k value; transmit, tothe UE, a message on a physical downlink shared channel (PDSCH) during afirst subframe (n-k); and receive a HARQ response associated with themessage from the UE during a second subframe (n).
 20. The BS of claim13, wherein the information element is transmitted in a first subframe,wherein the information on the UL-DL configuration change is transmittedin a second subframe, wherein the first subframe is prior to the secondsubframe.